20748684637 has 4 divisors (see below), whose sum is σ = 21969195516. Its totient is φ = 19528173760.

The previous prime is 20748684613. The next prime is 20748684643. The reversal of 20748684637 is 73648684702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 11255300281 + 9493384356 = 106091^2 + 97434^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20748684637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20748684137) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 610255414 + ... + 610255447.

It is an arithmetic number, because the mean of its divisors is an integer number (5492298879).

Almost surely, 2^20748684637 is an apocalyptic number.

It is an amenable number.

20748684637 is a deficient number, since it is larger than the sum of its proper divisors (1220510879).

20748684637 is a wasteful number, since it uses less digits than its factorization.

20748684637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1220510878.

The product of its (nonzero) digits is 10838016, while the sum is 55.

The spelling of 20748684637 in words is "twenty billion, seven hundred forty-eight million, six hundred eighty-four thousand, six hundred thirty-seven".